In a dental clinic, a dental unit in which various treatment instruments and treatment goods are arranged around a dental chair is installed. The dental unit includes, as treatment instruments using water, a handpiece for grinding a tooth (tooth grinding tool), a scaler for removing tartar (tartar removing tool), a syringe for cleaning a mouth (mouth cleaning tool), and the like to which service water is supplied.
In the case where the dental unit is installed in a room of a building, a connection box for relay in the dental unit, a tap of a washstand, and the like are connected to a waterline which is branched from a main pipe for receiving supply of service water chlorinated in accordance with a predetermined environmental sanitation standard and which is led into the room.
To the connection box, an airline from a compressor for discharging compressed air is usually also connected. The airline and the waterline are connected to a control center via the unit body.
To the control center, a plurality of tubes whose tips are provided with the handpiece, the syringe, and a vacuum cleaner for discharging water are connected, and a lead wire from a foot switch and the like is also connected.
When any of the switches of the instruments is turned on at the time of treatment, the control center transmits high-pressure water to the handpiece side via the tube and the high-pressure water rotates a turbine cutter attached to the head of the handpiece, thereby enabling grinding of a tooth. The control center also supplies low-pressure water to the syringe via the tube so that the water is injected into the mouth. In such a manner, tooth treatment can be performed by using service water.
In the waterline connected to the dental unit, differently from a general water pipe, microbia and bacteria easily propagate themselves. It is feared that the water used for treatment of teeth is bad for the health of the patient.
Specifically, each of the waterlines to the handpiece, syringe, scaler, a water supplier for rinsing out the mouth, and the like from which water is supplied directly to the mouth of a patient is branched in some midpoint and its diameter decreases toward the end side. On the side of the treatment instruments connected to the waterlines, water is not always used. Therefore, retention time of the water in the waterlines tends to be long.
In dental clinics, the room temperature is maintained almost constant in all seasons. Consequently, even when the temperature of service water sent to the main pipe side is low, the water temperature in the waterlines rises by being influenced by the higher room temperature of the dental clinics. The environment of the internal wall face of the waterline is suitable for culturing microbia.
Consequently, even when the number of colonies of microbia and bacteria included in one milliliter of chlorinated service water is a few on the main pipe side as the source of water, it sharply increases on the waterline side of the dental unit in which the temperature is about room temperature. There is a case that the number of colonies increased to several hundreds of thousands on the end side of each of the waterlines attached to the various treatment instruments.
As described above, when microbia and bacteria increased in the waterline enter the body through the mouth of a patient at the time of treatment, they may cause various diseases and, what is more, a problem of hospital infection arises. Consequently, it has been expected that effective means for sterilizing water in a waterline used in a dental clinic, a dental department in a hospital, and the like is developed.
An object of the invention is to provide an apparatus and method for preventing growth of microbia and bacteria on an internal wall of a waterline of a dental unit or for removing them, thereby enabling a problem that the patient is infected in a clinic or hospital to be avoided.